text: #!/usr/bin/env python3
  # Copyright (c) 2017 The Bitcoin Core developers
  # Distributed under the MIT software license, see the accompanying
  # file COPYING or http://www.opensource.org/licenses/mit-license.php.
  """Test wallet replace-by-fee capabilities in conjunction with the fallbackfee."""
  from test_framework.test_framework import KazucoinTestFramework
  from test_framework.util import *
  
  class WalletRBFTest(KazucoinTestFramework):
      def set_test_params(self):
          self.num_nodes = 1
          self.setup_clean_chain = True
  
      def run_test(self):
          self.nodes[0].generate(101)
  
          # sending a transaction without fee estimations must be possible by default on regtest
          self.nodes[0].sendtoaddress(self.nodes[0].getnewaddress(), 1)
  
          # test sending a tx with disabled fallback fee (must fail)
          self.restart_node(0, extra_args=["-fallbackfee=0"])
          assert_raises_rpc_error(-4, "Fee estimation failed", lambda: self.nodes[0].sendtoaddress(self.nodes[0].getnewaddress(), 1))
          assert_raises_rpc_error(-4, "Fee estimation failed", lambda: self.nodes[0].fundrawtransaction(self.nodes[0].createrawtransaction([], {self.nodes[0].getnewaddress(): 1})))
          assert_raises_rpc_error(-6, "Fee estimation failed", lambda: self.nodes[0].sendmany("", {self.nodes[0].getnewaddress(): 1}))
  
  if __name__ == '__main__':
      WalletRBFTest().main()
  